1. Filed of the Invention
The present invention relates to a positive type photoresist developer and more particularly to a photoresist developer comprising an aqueous solution of quaternary ammonium hydroxide containing hydrazine or hydrazine and a nonionic surfactant. Especially it relates to a positive type resist developer which enables the formation of a fine pattern having a high degree of resolution (high resolving power) and can provide an excellent profile with few irregularities in pattern dimensions, and thus which is useful for production of semiconductor integrated circuits and so forth.
2. Description of the Related Arts
With the marked development of the electronic industry in recent years, the semiconductor integrated circuit has increased in the degree of integration as exemplified by a super LSI, and the minimum line width in drawing a circuit is more decreased. Under such circumstances, it has been strongly desired to form a resist pattern with high fidelity. Only a positive type resist can meet the above requirements and moreover it is superior in degree of resolution to the conventionally used negative type resist. A typical positive type resist contains an alkali-soluble novolak resin and a naphthoquinonediazide compound as a photo-decomposable agent.
In this positive type resist containing a naphthoquinonediazide compound, an aqueous alkali solution is used as a developer. In the production of semiconductor integrated circuit devices, it is undesirable to use an aqueous alkali solution containing metal ions as a developer. For this reason, a developer of organic alkali not containing metal ions, for example, an aqueous solution of tetramethylammonium hydroxide (IBM, Technical Disclosure Bulettin, Vol. 13, No. 7, p. 2009(1970)) or choline (U.S. Pat. No. 4,239,661) is generally used.
However, in the drawing of a pattern with a fine line width using a developer of, e.g., tetramethylammonium hydroxide or choline, a resist profile and a dimension controlling accuracy are extremely decreased. Thus, in order to increase resist accuracy, an alkali concentration of a developer is increased, or a developer temperature is increased, or a developing time is lengthened. However, no sufficient effect for so-called through put can be obtained. As an improved technique to increase a degree of resolution, it is proposed to add various surfactants or organic compounds to an aqueous solution of quaternary ammonium hydroxide. Addition of surfactants is disclosed in Japanese Patent Application Laid-Open Nos. 9143/1983, 70551/1986, 151537/1986, 16748/1986, 232453/1986, 232454/1986, 32452/1987, 32454/1987, 47125/1987, etc. Addition of surfactants and organic compounds such as alcohols and hydrocarbons is disclosed in Japanese Patent Application Laid-Open Nos. 232453/1987, 57128/1983, etc. Addition of other organic compounds are disclosed in Japanese Patent Application Laid-Open Nos. 24105/1985, 38755/1987, 57162/1987, 67535/1987, etc. However, these aqueous solutions have advantages and disadvantages, and cannot always be satisfactory in degree of resolution, dimensional accuracy and so forth in lithography of fine line width patterns.
In order to increase storage stability of an aqueous choline solution and to prevent coloration thereof, an aqueous solution obtained by adding hydrazine to an aqueous choline solution has been proposed (Japanese Patent Application Laid-Open No. 63643/1988).
The present inventors have disclosed that an aqueous solution prepared by mixing an aqueous solution of quaternary ammonium hydroxide with hydrazine and a surfactant is useful for a washing solution for wafers (Japanese Patent Application No. 169653/1987). As a result of a further study on a positive type photoresist developer capable of providing a profile which is of high degree of resolution, is decreased in irregularities in pattern dimensions, and is high in accuracy, it has been found that addition of hydrazine or hydrazine and a nonionic surfactant to an aqueous quaternary ammonium hydroxide solution as an aqueous organic alkali solution enables the formation a fine pattern with high accuracy. The present invention has been accomplished based on the findings herein.